Justin Fields #1 of the Chicago Bears runs the ball...

Justin Fields #1 of the Chicago Bears runs the ball during the second quarter against the Atlanta Falcons at Mercedes-Benz Stadium on Nov. 20, 2022 in Atlanta. Credit: Getty Images/Kevin C. Cox

FLORHAM PARK, N.J. — Defending against Justin Fields is a challenge. Not knowing whether you will have to defend against him is a different kind of challenge.

But coach Robert Saleh said on Friday that his Jets will be ready regardless of whether the Bears start the injured Fields at quarterback Sunday at MetLife Stadium.

“We’re preparing for him,” Saleh said before practice on Friday. “If he plays, we’ll hit him. If he doesn’t play, we’ll do our best to hit the next guy.”

The “next guy” would be former Jet Trevor Siemian, who last won an NFL start in 2017 and is far less of a running threat than Fields is.

So much so that Jets defensive coordinator Jeff Ulbrich dispensed with standard coach-speak and said the Bears’ two options are completely different cats who require different approaches.

“It’s challenging,” Ulbrich said. “You have to have contingency plans both ways. We’ve kind of devoted a little bit of time to both. We will be prepared for both.”

Fields suffered a separated left (non-throwing) shoulder and what he described as partially torn ligaments in Sunday’s loss to Atlanta and practiced on a limited basis this week. He is listed as questionable.

Fields has 13 touchdown passes and eight interceptions, but he has drawn leaguewide attention for his 834 rushing yards — fifth in the NFL behind four running backs. In his past five games, he has rushed for six touchdowns. In his past three games, he has rushed for 178, 147 and 85 yards.

“He is probably one of the most dynamic runners,” Ulbrich said, “and that’s not just quarterback, that’s wide receiver, running back, whatever the case in the NFL right now.”

Linebacker C.J. Mosley called Fields “electrifying” and said he reminds him of Lamar Jackson, a teammate with the Ravens in 2018.

Sunday’s subplot is that some draft observers thought the Jets should have taken Fields at No. 2 overall in 2021. Instead, they chose Zach Wilson, and Fields fell to No. 11.

Now Wilson will watch from the sideline Sunday to “reset” while Mike White starts.

Asked what he thought of Fields pre-draft, Saleh said: “Thought he was big, strong, obviously he’s got all the athleticism. He’s really come into his own. They’ve done a really good job with regards to the added dimension of the run game. He’s getting better as a passer, but his off-schedule running, the QB run game, it’s a problem, for sure.”

Saleh said facing other mobile quarterbacks such as the Bills’ Josh Allen should help the Jets be ready for Fields if he plays. Ulbrich said he gained valuable experience while on the Falcons’ staff during Cam Newton’s heyday in the late 2010s, when Atlanta faced Newton’s Panthers twice a season. Like Newton, Fields is more than just a runner.

“He’s a guy with phenomenal arm talent, which he doesn’t get enough credit for,” Ulbrich said. “I think he’s growing as far as seeing the game and understanding the game, but the arm talent is obviously there. He can throw a deep ball. He’s got great touch and feel and power. He’s got receivers who can go get it. He’s a very interesting challenge for us.”

Notes & quotes: DL Sheldon Rankins (elbow) is out and TE Kenny Yeboah (calf) is doubtful .  .  . Even with WR Corey Davis returning from injury, Saleh said Denzel Mims likely will be active. “There’s still a role,” he said.“He’s earned that role.”

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